#include<iostream>
using namespace std;
int main(){
    double n;
    cin >> n;
    double l = -10000, r = 10000;
    while(r - l > 1e-8){//要求保留几位小数就在此基础上加2
        double mid = (l + r) / 2;
        if(mid * mid * mid >= n) r = mid;
        else l = mid;
    }
    printf("%lf", l);
    return 0;
}